This invention relates to high power surface acoustic wave devices and methods of fabrication.
In the present communication age, more and more emphasis is being placed on wireless communications and particularly on small handheld communication devices, such as two-way radios, cellular telephones, etc. Because of the ever increasing need, or desire, to make these handheld devices smaller, it is imperative that various components within the devices be made smaller. Traditionally, in the past, components such as filters have been difficult to miniaturize and many attempts have resulted in inferior components which either do not have a sufficiently long life or cannot withstand the power requirements.
Surface acoustic wave (SAW) devices have been known for a long time and relatively recently have been incorporated as filters into the front end of handheld communication devices. It is well known in the art that SAW devices can be fabricated very frequency sensitive so that they make excellent filters. However, the size of the SAW device is dependent upon the operating frequency, i.e. the higher the frequency the smaller the SAW device. The major problem that arises is that the SAW filters must be made very small because of the very high radio frequencies that are being used in the various communication systems. In addition to the size requirement, the present handheld devices transmit relatively high power (e.g. a watt or more). Thus, the SAW filters are becoming smaller while the power handling requirement remains high. Thus, the SAW fabrication materials and techniques must be continually improved.
Accordingly it is highly desirable to provide SAW devices with improved materials and fabrication methods which result in small SAW devices with relatively large power handling capabilities and longer life.